Are patients with rheumatoid arthritis still at an increased risk of tuberculosis and what is the role of biological treatments?

Objective: To estimate the risk of tuberculosis (TB) in patients with rheumatoid arthritis (RA) both with and without exposure to biological therapy and to directly compare the risks between therapies.

Methods: Data from the Swedish National Population Registers, Tuberculosis Register and the Swedish Biologics Register were used to conduct a prospective population-based national cohort study (2002-2011). We estimated the rate of incident TB in the general population and in a cohort of biological-naïve and biological-exposed patients diagnosed with RA. Cox models were used to estimate HRs with particular attention to risks by calendar and follow-up time and individual biologics.

Results: Compared to the general population, RA patients not exposed to biologicals had a fourfold increased risk of TB (HR 4.2; 95% CI 2.7 to 6.7), which did not decline over calendar time. In contrast, the risk of TB in the biological-exposed RA population decreased since 2002 compared with biological-naïve; from HR=7.9 (95% CI 3.3 to 18.9) in 2002-2006 to HR=2.4 (95% CI 0.9 to 6.1) in 2007-2011. The HRs for most recent exposure to adalimumab and infliximab compared with etanercept were 3.1 (95% CI 0.8 to 12.5) and 2.7 (95% CI 0.7 to 10.9), respectively, and the HR for etanercept compared with biological-naïve RA was 1.7 (95% CI 0.6 to 4.6).

Conclusions: In the past decade, the risk of TB has decreased among biological-exposed RA patients but remains higher than in biological-naïve RA patients. Most cases of TB in RA occur in biological-naïve RA patients, underscoring the elevated risk also in these patients.